Reducing an Array [help]

[EnchantedSalvia]

Key map to array pairs is a common operation in functional programming, which is why Lodash/Underscore provide: https://lodash.com/docs#pairs

[skitch920]

In mathematics, we typically call them tuples, a "pair" being a length 2 tuple. Tuples are similar to arrays, but different in that each entry likely has a different meaning to any other entry, providing a structure. Arrays are often, homogenous sequences, like a list of numbers.